Solar collectors gather direct and limited ambient sunlight and direct it toward a target area. Active solar collector systems employ a mechanism for tracking the sun's trajectory across the sky to maximize the amount of sunlight collected. Active systems may be highly efficient solar collectors, however the required tracking mechanisms add complexity and expense to the system. By contrast, passive solar collector systems employ a fixed reflector system to direct light toward a target area. Passive systems are relatively less complex and less expensive, however passive systems are generally less efficient than active systems.
Daylighting systems are a particular type of solar collector which may be used to provide illumination for the interior of a building by directing daylight into the building. Daylight, as used in connection with the present invention, includes all forms of sunlight whether direct or ambient. Because of cost constraints, most daylighting systems are passive systems which employ fixed reflectors and/or refractors to direct daylight through an aperture into a building.
Conventional skylights mounted on conventional curbs suffer from glare when the sun is low in the sky, i.e., when the sun's elevation angle is small. For such prior-art skylights and curbs, sunlight can enter the building at an angle closer to horizontal than vertical, and such light can enter the eyes of people inside the building, causing discomfort. Previous attempts to solve this problem have sometimes used diffusing domes at the top of the skylight or diffusing windows at the bottom of the skylight, or both. These diffusing domes and windows are expensive and they also suffer major optical losses in transmitting the sunlight into the building. None of these previous attempts to solve the low sun elevation angle glare problem have provided high optical efficiency, low cost, and adequate glare prevention.
The present subject matter minimizes the low sun elevation angle glare problem while also providing high optical efficiency and low cost. The present subject matter uses a simple curved reflective insert in the curb supporting the skylight. The curved reflective insert spreads the incident low sun elevation angle light widely in the azimuthal direction, thereby minimizing glare. The only optical loss is related to the reflectance of the mirror material, which can be 95% or higher with available cost-effective reflective materials. Furthermore, for high sun elevation angle light, the reflective insert does not intercept much of this light and therefore causes extremely small optical losses.
The present subject matter can take many different forms, from a single curved reflector to multiple curved reflectors, and each reflector can have a variety of different curved shapes. The reflectors in the present disclosed subject matter are specularly reflective on both sides, and they are placed inside the curb of the skylight, making the reflectors simple, easy to make and install, and therefore very economical. The reflectors can be installed in the curb below any type of skylight, making them very adaptable to a variety of applications, from big-box stores to offices to residences.
The present subject matter represents a unique new skylight curb insert employing curved reflectors to minimize glare from low sun elevation angle skylights.
In one embodiment the disclosed subject matter is a unique skylight curb insert comprising one or more curved reflective surfaces to spread low sun elevation angle sunlight in the azimuthal direction to minimize glare from the skylight into the building below. This disclosed subject matter is simple, easy to manufacture, easy to install, and therefore extremely cost-effective. The disclosed subject matter provides outstanding optical throughput efficiency.
An embodiment includes a light passage for providing daytime lighting to a building, the light passage includes a curb defining the lateral boundaries of a light passage into an interior of the building; wherein the lateral boundaries extend from an interior opening in the building to an exterior opening outside the building. The light passage further includes a strip within the curb, the strip having a length and width which define at least one surface which is reflective, the width extending vertically from the interior opening towards the exterior opening of the curb; and wherein the strip is curved along the length such that the radius of curvature of the curve is perpendicular to vertical.
In another embodiment the light passage includes a strip within the curb, the strip having a length and width which define at least one surface which is reflective, the width extending vertically from the interior opening towards the exterior opening of the curb; and wherein the strip is bent such that the edge defining the bend is vertical.
In still another embodiment the disclosed subject matter is a diffusing dome with a pyramid reflector and diffuser that is economically superior to a clear dome with pyramid reflector.
In yet another embodiment, the disclose subject matter is a diffusing dome and a diffuser with no reflector which is economically superior to a clear dome with pyramid reflector.